ACUTE POISONING IN ADULTS

Leilah Dare

SpR Emergency Medicine

Acute Poisoning in the Emergency Department

• Common - 3-5% of ED attendances

• 2000 Deaths per year

• Some of the highest rates of deliberate poisoning in Europe

• Often multiple drugs

• DON’T FORGET ALCOHOL !!

Summary of Lecture

• General Principles in the Management of ANY Poisoning

• Specific management options with certain substances– Paracetamol– Opiates (Heroin, Methadone, Morphine)– Salicylates (Aspirin)– Tricyclic Antidepressants (e.g Dothiepin)

General Management -History

• Applies to ANY episode of Poisoning

• WHAT

• HOW MUCH (Ideally mg/Kg)

• WHEN

• WHAT ELSE (Including Alcohol)

• WHY

• Use Paramedics, friends, relatives, anyone!!

General Management -1

• A (Airway)

• B (Breathing)

• C (Circulation)

• D (Disability-AVPU/ Glasgow Coma Scale)

• DEFG ( Don’t ever forget the Glucose)

• GET A SET OF BASIC OBSERVATIONS

General Management -2

• Use all your senses, search for the clues• LOOK

– Track Marks– Pupil Size

• FEEL– Temperature, Sweating

• SMELL– Alcohol

Specific Management Options-1

• DECREASING DRUG ABSORPTION– Gastric Lavage ( Unpopular - need to protect

the airway, may push drug through pylorus into small bowel.)

– Absorbants ( Activated Charcoal , usually within 1 hour of ingestion, longer repeated doses in drugs that delay gastric emptying e.g. Aspirin)

Specific Management Options -2

• INCREASING DRUG ELIMINATION– Alkaline Diuresis (Aspirin)

– Haemodialysis (Aspirin)

Specific Management Options - 3

• ANTAGONISING THE EFFECTS OF THE POISON

– Desferrioxamine (IRON)– Naloxone (OPIATES)– N Acetylcysteine (PARACETAMOL)

Specific Poisons- Paracetamol

• Commonest drug used

• 50% of all Self Poisoning Episodes

• 100- 200 deaths per year

• DANGEROUS AND PEOPLE DON’T KNOW IT. YOU FEEL WELL AND THEN THE LIVER FAILURE SETS IN..

Paracetamol-Normal Metabolism

• Paracetamol converted to:

• N-Acetyl-p-benzoquinonamine (TOXIC)

• This is conjugated with Glutathione

• Glutathione stored in the body

• Produces a NON TOXIC metabolite

Paracetamol Metabolism in Overdose

• Glutathione stores are used up by the excess Paracetamol

• Toxic Metabolite build up

• Binds IRREVERSIBLY to Hepatic Cell membranes

• Resulting in LIVER NECROSIS

Paracetamol Overdose-management

• Initial ABC ( usually well systemically)

• Get a good history– TIME TAKEN, AMOUNT– Any other medication– History of Liver disease

• N-Acetylcysteine. Shown to be advantageous if given in the first 10 hours

N - Acetylcysteine

• Specific antidote used for Paracetamol

• Provides the Sulphydryl groups needed to increase the availability of Glutathione

• So that Body can turn the TOXIC metabolite into the non toxic form and prevent Liver Cell Damage and NECROSIS

• Problem: Not shown to be effective after 15 hours

Paracetamol Management

• Able to measure levels of Paracetamol in the blood.

• Helps to guide whether amount taken is enough to be Hepatotoxic

• IF IN DOUBT start treatment before the Paracetamol levels get back to save time

Paracetamol Management-Pitfalls

• Patients with Liver Disease/ Alcoholics– Depleted stores of Glutathione will start to get

toxic build up sooner than healthy people

• Staggered Overdoses– Levels unreliable

• After 15 hours- what do you do??

Paracetamol Management

• TIMEBOMB WAITING TO HAPPEN

• IF HAVE LATE PRESENTATION HAVE TO MONITOR FOR IMPENDING LIVER FAILURE

• REFER TO SPECIALIST LIVER UNIT

• PEOPLE DIE FROM THIS

Opiate Poisoning- Features

• Common (particularly in BRI)

• Heroin, Methadone, Analgaesics in Elderly

• Action on the mu receptors giving the effects in overdose.– 1. PINPOINT PUPILS– 2. RESPIRATORY DEPRESSION– 3.COMA

Opiate Overdose-Management

• INITIAL MANAGEMENT

• A

• B

• C

• D

Opiate Overdose-Management 2

• NALOXONE– Opioid antagonist– High Affinity for the opiate receptors– Little other effects– Rapid onset– Effects last 2-4 hrs, may need repeated doses– Give I-M or I-V

Salicylate (Aspirin) Poisoning

• Toxicity occurs due to disturbance in Acid-Base Balance

• 1. Respiratory Alkalosis

• 2. Metabolic Acidosis

Aspirin Poisoning- mechanism 1

• 1.Direct stimulation of the respiratory centre makes you overbreathe. Hyperventilation and Respiratory Alkalosis.

• 2. Kidney attempts to compensate for the alkalosis by excreting alkali to give you a metabolic Acidosis

• 3. Aspirin inhibits the normal metabolic pathways

Aspirin poisoning- mechanism 2

• 3. Aspirin inhibits the normal metabolic pathways, so you get failure of the normal metabolism of CHO, Fats and Protein.– Build up of Organic Acids– KETONES, LACTATE AND PYRUVATE– CAUSES MORE METABOLIC ACIDOSIS

• METABOLIC ACIDOSIS, BAD NEWS

Aspirin Poisoning -Clinical Features

• COMMON FEATURES:– Vomiting, Dehydration, Tinnitus, Vertigo– Sweating, Bounding pulses, Hyperventilation

• UNCOMMON FEATURES:– Confusion, Disorientation, Coma, Convulsions– Haematemesis, Hyperpyrexia, clotting

abnormalities, renal failure

Aspirin Overdose-Management

• Initial Supportive therapy. If small amounts and asymptomatic may need no treatment

• Management tailored according to the amount taken

• Able to take Salicylate levels to help guide treatment options

Aspirin Management - General

• A

• B

• C

• D

• (EFG)

Aspirin Management - Specific

• When extremely high levels of Aspirin have been ingested and the patients are symptomatic steps may be taken to-

• 1. DECREASE ABSORPTION

• 2. INCREASE DRUG ELIMINATION

Aspirin- Decreasing absorption

• Activated Charcoal– Given in those who have taken more than

250mg/Kg body weight less than 1 hour ago

• Gastric Lavage– May be considered in those who have taken

more than 500mg/kg body less than 1 hour ago. Steps must be taken to protect the airway

Aspirin-Increasing Drug Elimination

• Urinary Alkalinisation– If you increase urinary pH from 5 to 8 there is a

10-20 fold increase in the renal salicylate clearance

– This is done by giving an infusion of Sodium Bicarbonate. Care must be taken because this in itself is dangerous and can cause severe Acid Base Disturbances

Aspirin- Increasing Drug Elimination

• HAEMODIALYSIS

– Used in severe life threatening overdose– Aims to correct the Acid Base disturbances

while removing the Salicylate

Tricyclic Antidepressants

• Seen relatively frequently

• Can be fatal

• Can be very symptomatic, effects made worse by alcohol

• Main effects are on the Heart and Brain

• Effects are– 1. Anticholinergic– 2. Quinidine like

TCA Overdose- Clinical features

• ANTICHOLINERGIC EFFECTS– Dry Mouth, Dry Eyes, Dilated Pupils, Urinary

Retention, Blurred Vision, Dizziness, Palpitations, Pyrexia without sweating

– CNS Effects- Confusion, Delerium, Coma, Convulsions, Myoclonus and Respiratory Depression

TCA Overdose Clinical Features

• Cardiac Toxicity (quinidine effects)– Heart Block, Asystole, Bradycardia,

Tachycardia, Ventricular Dysrythmias– ECG Changes - broadening of QRS complex,

Widened QT Interval

TCA Overdose- Management 1

• Mainstay of initial management is Supportive. Try not to give other drugs ontop with a few specific exceptions

• A- May need intubating

• B

• C- Give IV fluids if low BP

• D -Control convulsions with Diazepam

TCA Overdose Management 2

• Activated Charcoal if more than 4 mg/Kg within 1 hour.– N.B WATCH OUT FOR THE AIRWAY

• Correct Hypoxia with Oxygen

• Correct Acidosis with Na Bic

• Correct any arrythmias with Na Bic (i.e start by controlling the acid base disturbance)

QUESTIONS

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SUMMARY

• Get as much history as you can, know your enemy

• Mainstay of any poisoning is Supportive

• Don’t Forget the ABC

• For specific substances there maybe antidotes

• For Specific circumstances consider decreasing the absorption or increasing the elimination of the drug.